Revert "use updated grit"

This reverts commit 3f6ed02b3a.

Gemfile

@@ -30,7 +30,7 @@ gem 'state_machine', '~> 1.2'
 gem 'redis-rails', '~> 4.0'
 
 gem 'grack', git: 'git://github.com/rosa-abf/grack.git', require: 'git_http'
-gem 'grit', git: 'git://github.com/rosa-abf/grit.git', tag: '2.6.13'
+gem 'grit', git: 'git://github.com/rosa-abf/grit.git'
 gem 'charlock_holmes', '~> 0.7'
 gem 'github-linguist', '~> 3.1', require: 'linguist'
 gem 'diff-display', '~> 0.0.1'

Gemfile.lock

@@ -40,14 +40,12 @@ GIT
 
 GIT
   remote: git://github.com/rosa-abf/grit.git
-  revision: a28b4c059f4d2fa66e59bb998f4250affeed286c
-  tag: 2.6.13
+  revision: 87e7cc875de5fd1c3e446d1fd0f533a95d10bb2d
   specs:
-    grit (2.7.1)
-      charlock_holmes (~> 0.6)
+    grit (2.5.0)
       diff-lcs (~> 1.1)
       mime-types (~> 1.15)
-      posix-spawn (~> 0.3)
+      posix-spawn (~> 0.3.6)
 
 GEM
   remote: https://rubygems.org/